Hemophagocytosis in EBV-infected NOG-hCD34 mice. (A-B) Hemophagocytosis in the BM of EBV-infected mice. The specimens of the BM fluid smear of EBV-infected mice were prepared and assessed by NSE staining (A) and Giemsa staining (B). (A) NSE staining. Histiocytes (brown) and neutrophils (blue) were stained. Areas enclosed with squares (i-iii) indicate the histiocytes with granules and are, respectively, enlarged in panels i through iii. (B) Giemsa staining. A representative histiocyte with phagocytosis is shown. Arrowheads indicate engulfed erythrocytes. (C-D) Hemophagocytosis in the spleen and hepatic sinusoid of EBV-infected mice. Tissue sections were assessed by H&E staining (C) and Berlin blue staining (hemosiderin staining; D). (C) H&E staining. Representatives of spleen (top) and liver (bottom) of mock-infected mice (left) and EBV-infected mice (right) are shown. Areas enclosed with squares are enlarged in the bottom right of each panel and indicate morphologically activated histiocytes. (D) Berlin blue staining. Representatives of spleen (top) and liver (bottom) of EBV-infected mice are shown. Note that the cells stained with blue indicate hemosiderin-containing hemophagocytic histiocytes. Scale bars in panels C and D represent 50 μm.